The Experts below are selected from a list of 38622 Experts worldwide ranked by ideXlab platform

Stefano Sgobba - One of the best experts on this subject based on the ideXlab platform.

  • A Comparative Study of Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds
    Journal of Materials Engineering and Performance, 2018
    Co-Authors: I. Aviles Santillana, P. Fernandez Pison, S. A. E. Langeslag, A. T. Perez Fontenla, Elisa Maria Ruiz-navas, C. Boyer, Arnaud Foussat, Stefano Sgobba
    Abstract:

    The ITER magnet system is based on the “cable-in-conduit” conductor (CICC) concept, which consists of stainless steel jackets filled with superconducting strands. The jackets provide high strength, limited fatigue crack growth rate and fracture toughness properties to counteract the high stress imposed by, among others, electromagnetic loads at Cryogenic Temperature. Austenitic nitrogen-strengthened stainless steels have been chosen as base material for the jackets of the central solenoid and the toroidal field system, for which an extensive set of Cryogenic mechanical property data are readily available. However, little is published for their welded joints, and their specific performance when considering different combinations of parent and filler metals. Moreover, the impact of post-weld heat treatments that are required for Nb_3Sn formation is not extensively treated. Welds are frequently responsible for cracks initiated and propagated by fatigue during service, causing structural failure. It becomes thus essential to select the most suitable combination of parent and filler material and to assess their performance in terms of strength and crack propagation at operation conditions. An extensive test campaign has been conducted at 7 K comparing tungsten inert gas (TIG) welds using two fillers adapted to Cryogenic service, EN 1.4453 and JK2LB, applied to two different base metals, AISI 316L and 316LN. A large set of fracture toughness data are presented, and the detrimental effect on fracture toughness of post-weld heat treatments (unavoidable for some of the components) is demonstrated. In this study, austenitic stainless steel TIG welds with various filler metals have undergone a comprehensive fracture mechanics characterization at 7 K. These results are directly exploitable and contribute to the Cryogenic fracture mechanics properties database of the ITER magnet system. Additionally, a correlation between the impact in fracture toughness and microstructure resulting from the above treatment is provided.

  • Secondary Phases Quantification and Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds for High-Field Superconducting Magnets
    2017
    Co-Authors: Ignacio Aviles Santillana, S. A. E. Langeslag, C. Boyer, Stefano Sgobba, Pilar Fernandez Pison, Alexander Lunt, Elisa Maria Ruiz Navas
    Abstract:

    The ITER magnet system is based on the “cable-in-conduit” conductor concept, which consists of various types of stainless steel jackets filled with superconducting strands. The jackets provide high strength and fracture toughness to counteract the high stress imposed by, amongst others, electromagnetic loads at Cryogenic Temperature. Material properties of austenitic stainless steel at Cryogenic Temperature are known to some extent, but only partial information is available for their welds, particularly in combination with weld fillers envisaged for Cryogenic service. When a full inspection of the welded components is not possible, it becomes of special interest an assessment of its fracture toughness under close-to-service conditions if a fracture mechanics’ design approach is to be adopted. In absence of defects, brittle secondary phases are generally held responsible of the loss of ductility and toughness which is to be expected after postweld heat treatments. Their quantification becomes thus essential in order to explain the negative impact in fracture toughness after unavoidable thermal treatments. This paper investigates fracture toughness behavior at 7 K of AISI 316L and AISI 316LN tungsten inert gas welds using two fillers adapted to Cryogenic service, EN 1.4453 and JK2LB. Additionally, the effect of such an aforementioned heat treatment, here the Nb$_3$Sn reaction heat treatment (650° for 200 h) on fracture toughness of the welds is evaluated. A correlation between the evolution of properties and the quantity of secondary phases as a result of the above treatment is provided.

I. Aviles Santillana - One of the best experts on this subject based on the ideXlab platform.

  • A Comparative Study of Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds
    Journal of Materials Engineering and Performance, 2018
    Co-Authors: I. Aviles Santillana, P. Fernandez Pison, S. A. E. Langeslag, A. T. Perez Fontenla, Elisa Maria Ruiz-navas, C. Boyer, Arnaud Foussat, Stefano Sgobba
    Abstract:

    The ITER magnet system is based on the “cable-in-conduit” conductor (CICC) concept, which consists of stainless steel jackets filled with superconducting strands. The jackets provide high strength, limited fatigue crack growth rate and fracture toughness properties to counteract the high stress imposed by, among others, electromagnetic loads at Cryogenic Temperature. Austenitic nitrogen-strengthened stainless steels have been chosen as base material for the jackets of the central solenoid and the toroidal field system, for which an extensive set of Cryogenic mechanical property data are readily available. However, little is published for their welded joints, and their specific performance when considering different combinations of parent and filler metals. Moreover, the impact of post-weld heat treatments that are required for Nb_3Sn formation is not extensively treated. Welds are frequently responsible for cracks initiated and propagated by fatigue during service, causing structural failure. It becomes thus essential to select the most suitable combination of parent and filler material and to assess their performance in terms of strength and crack propagation at operation conditions. An extensive test campaign has been conducted at 7 K comparing tungsten inert gas (TIG) welds using two fillers adapted to Cryogenic service, EN 1.4453 and JK2LB, applied to two different base metals, AISI 316L and 316LN. A large set of fracture toughness data are presented, and the detrimental effect on fracture toughness of post-weld heat treatments (unavoidable for some of the components) is demonstrated. In this study, austenitic stainless steel TIG welds with various filler metals have undergone a comprehensive fracture mechanics characterization at 7 K. These results are directly exploitable and contribute to the Cryogenic fracture mechanics properties database of the ITER magnet system. Additionally, a correlation between the impact in fracture toughness and microstructure resulting from the above treatment is provided.

Thierry Grosdidier - One of the best experts on this subject based on the ideXlab platform.

  • on the effectiveness of surface severe plastic deformation by shot peening at Cryogenic Temperature
    Applied Surface Science, 2016
    Co-Authors: Marc Novelli, Jeanjacques Fundenberger, Philippe Bocher, Thierry Grosdidier
    Abstract:

    Abstract The effect of Cryogenic Temperature (CT) on the graded microstructures obtained by severe shot peening using surface mechanical attrition treatment (SMAT) was investigated for two austenitic steels that used different mechanisms for assisting plastic deformation. For the metastable 304L steel, the depth of the hardened region increases because CT promotes the formation of strain induced martensite. Comparatively, for the 310S steel that remained austenitic, the size of the subsurface affected region decreases because of the improved strength of the material at CT but the fine twinned nanostructures results in significant top surface hardening.

Marc Novelli - One of the best experts on this subject based on the ideXlab platform.

  • on the effectiveness of surface severe plastic deformation by shot peening at Cryogenic Temperature
    Applied Surface Science, 2016
    Co-Authors: Marc Novelli, Jeanjacques Fundenberger, Philippe Bocher, Thierry Grosdidier
    Abstract:

    Abstract The effect of Cryogenic Temperature (CT) on the graded microstructures obtained by severe shot peening using surface mechanical attrition treatment (SMAT) was investigated for two austenitic steels that used different mechanisms for assisting plastic deformation. For the metastable 304L steel, the depth of the hardened region increases because CT promotes the formation of strain induced martensite. Comparatively, for the 310S steel that remained austenitic, the size of the subsurface affected region decreases because of the improved strength of the material at CT but the fine twinned nanostructures results in significant top surface hardening.

S. A. E. Langeslag - One of the best experts on this subject based on the ideXlab platform.

  • A Comparative Study of Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds
    Journal of Materials Engineering and Performance, 2018
    Co-Authors: I. Aviles Santillana, P. Fernandez Pison, S. A. E. Langeslag, A. T. Perez Fontenla, Elisa Maria Ruiz-navas, C. Boyer, Arnaud Foussat, Stefano Sgobba
    Abstract:

    The ITER magnet system is based on the “cable-in-conduit” conductor (CICC) concept, which consists of stainless steel jackets filled with superconducting strands. The jackets provide high strength, limited fatigue crack growth rate and fracture toughness properties to counteract the high stress imposed by, among others, electromagnetic loads at Cryogenic Temperature. Austenitic nitrogen-strengthened stainless steels have been chosen as base material for the jackets of the central solenoid and the toroidal field system, for which an extensive set of Cryogenic mechanical property data are readily available. However, little is published for their welded joints, and their specific performance when considering different combinations of parent and filler metals. Moreover, the impact of post-weld heat treatments that are required for Nb_3Sn formation is not extensively treated. Welds are frequently responsible for cracks initiated and propagated by fatigue during service, causing structural failure. It becomes thus essential to select the most suitable combination of parent and filler material and to assess their performance in terms of strength and crack propagation at operation conditions. An extensive test campaign has been conducted at 7 K comparing tungsten inert gas (TIG) welds using two fillers adapted to Cryogenic service, EN 1.4453 and JK2LB, applied to two different base metals, AISI 316L and 316LN. A large set of fracture toughness data are presented, and the detrimental effect on fracture toughness of post-weld heat treatments (unavoidable for some of the components) is demonstrated. In this study, austenitic stainless steel TIG welds with various filler metals have undergone a comprehensive fracture mechanics characterization at 7 K. These results are directly exploitable and contribute to the Cryogenic fracture mechanics properties database of the ITER magnet system. Additionally, a correlation between the impact in fracture toughness and microstructure resulting from the above treatment is provided.

  • Secondary Phases Quantification and Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds for High-Field Superconducting Magnets
    2017
    Co-Authors: Ignacio Aviles Santillana, S. A. E. Langeslag, C. Boyer, Stefano Sgobba, Pilar Fernandez Pison, Alexander Lunt, Elisa Maria Ruiz Navas
    Abstract:

    The ITER magnet system is based on the “cable-in-conduit” conductor concept, which consists of various types of stainless steel jackets filled with superconducting strands. The jackets provide high strength and fracture toughness to counteract the high stress imposed by, amongst others, electromagnetic loads at Cryogenic Temperature. Material properties of austenitic stainless steel at Cryogenic Temperature are known to some extent, but only partial information is available for their welds, particularly in combination with weld fillers envisaged for Cryogenic service. When a full inspection of the welded components is not possible, it becomes of special interest an assessment of its fracture toughness under close-to-service conditions if a fracture mechanics’ design approach is to be adopted. In absence of defects, brittle secondary phases are generally held responsible of the loss of ductility and toughness which is to be expected after postweld heat treatments. Their quantification becomes thus essential in order to explain the negative impact in fracture toughness after unavoidable thermal treatments. This paper investigates fracture toughness behavior at 7 K of AISI 316L and AISI 316LN tungsten inert gas welds using two fillers adapted to Cryogenic service, EN 1.4453 and JK2LB. Additionally, the effect of such an aforementioned heat treatment, here the Nb$_3$Sn reaction heat treatment (650° for 200 h) on fracture toughness of the welds is evaluated. A correlation between the evolution of properties and the quantity of secondary phases as a result of the above treatment is provided.